Remove front-end if it is not needed

Thank you so much for developing such a useful module for decoupled websites with a Drupal based back-end!

Sorry for the title, actually this issue is just in case someone finds it useful, not to integrate into the module. I'm using search_api_lunr to integrate Fuse.js in a custom way in the front-end with Drupal in the back-end generating statics because Lunr is unmaintained.

The problem appears to me when in the statics are generated a number of JavaScript dependencies and paths related to Lunr, and to optimize the performance of the web, I decided to remove them from the module.

As I said, this issue is not to integrate into the module, I simply share the patch in case someone is in my situation and needs a patch to remove the entire front end of search_api_lunr and use only the indexing system with Search API.